k-dependent electronic structure of NiNmSb single-crystal surfaces

The half-Heusler alloy NiMnSb is believed to be a half-metallic ferromagnet with 100{\%} spin polarization at the Fermi level. This property makes it an interesting material for spintronic applications. Detailed~understanding~of~the~band~structure~of NiMnSb,~not~only~in~the~bulk~but~also~at~surfaces~and~interfaces,~is essential~to~developing~spintronic~applications. To date, however, the only data available are of the density of states, specifically from polycrystalline samples. We present angle-resolved photoemission results from both the $\bar {\Gamma }\bar {X}$ and $\bar {\Gamma }\bar {K}$ directions of a carefully prepared and surface-characterized NiMnSb(100) single crystal. We observed clear energy dispersion of occupied bulk states as a function of the wave vector parallel to the surface. We distinguish between bulk and surface states in our one-step-model calculations. Our results are discussed along with band structure calculations.